One of the early techniques for preparing linear polyalkylene polyamine compounds, such as diethylenetriamine and triethylene tetramine and higher homologues, has been to react an alkyl halide with an amine such as ammonia, ethylenediamine and the like at elevated temperatures and pressures. Generally, high yields of cyclic polyethylene polyamines, e.g. piperazine, triethylenediamine as well as other cyclic amines were produced. Another problem in the process was that hydrohalide salts of ammonia or hydrogen chloride were produced by the reaction, and thus expensive corrosion resistant equipment was required. U.S. Pat. No. 3,751,474 is representative.
More recently a series of patents have issued which disclose the preparation of linear polyalkylene polyamine compounds by reacting a diol or an alkanolamine compound with an alkylenediamine compound under preselected process conditions to produce linear alkylene polyamines. These include:
U.S. Pat. No. 3,714,259, which shows preparing linear poly(ethylene)amines by contacting ethanolamine with an ethylenediamine compound in the presence of hydrogen and hydrogenation catalyst. An example of a hydrogenation catalyst is nickel containing copper and chromium components;
U.S. Pat. No. 4,036,881, which shows the preparation of polyalkylene polyamines by reacting an alkanolamine with an alkylene amine compound in the presence of a phosphorous-containing substance selected from the group consisting of acidic metal phosphates, phosphoric acid compounds and hydrides and phosphate esters; and
U.S. Pat. No. 4,044,053, which is somewhat similar to the U.S. Pat. No. 4,036,881 patent except that the alkylene amine compound is present in an excess amount and a diol is used in place of the alkanolamine.